Power generating method of carbon-molecule gasification combustion boiler

ABSTRACT

A power generating method of Carbon-molecule gasification combustion, the method comprising the following main processes: taking coal with desulfurizing agent, and first conducting desulfirization and gasification in a molecular gasifier to produce clean coal gas; mixing hot coal gas and low excess air for combustion in the furnace of a boiler; conducting coke refining and dust removal in accordance with coal quality and demand; after heat transfer via the heated surface of the boiler, emitting high temperature flue gas complying with the standard from the chimney; and the vapor generated by the boiler drives a steam turbine to generate power. The gasification method can be applied to a power generating system of a gas engine and a gas turbine to produce desired cooling coal gas, and can also produce chemical feed gas. The method has a simple process, which is energy saving.

CROSS-REFERENCE OF THE INVENTION APPLICATION

The invention application claims priority of two Chinese invention applications: an application whose application NO. is 201310653009.8 and title is a method of carbon molecular gasification combustion in coal based boiler of electricity plant and an application whose application NO. is 201410400491.9 and title is a power generating method of carbon molecular gasification combustion boiler (furnace).

TECHNICAL FIELD

The present invention relates to a clean coal combustion power generating method, in particular a power generating method of a gasification combustion boiler designed in the level of molecule of the coal.

BACKGROUND ART

Nowadays, climate change, environmental deterioration and resources shortages are world wide problems. Saving energy, reduction of discharge and adaptation to the climate change have already become hot topics and focus of world politics from technology.

The current status of China is a county of energy production and consumption mainly depending on coal due to more coal, less gasoline and shortage of natural gas. The consumption of coal already is half of total amount of world consumption of coal and in more than 80% thereof, the traditional direct combustion type (grate laminar flow, fluid bed combustion, powdered coal combustion, briquette and coal water slurry) is still utilized. The environment scientist believes that the direct combustion type is also a main pollution source causing dust-haze in current China.

However, the direct coal combustion type will still be utilized worldwide, such as the power generating method of the coal combustion with high efficiency and low discharge, in 2021-2050 indicated by International Energy Bureau will still adopt the direct combustion technology of the recycling fluidization bed boiler and powered coal boiler. China also sees the recycling fluidization bed boiler and powered coal boiler as an important technology in the future. These come from unrealization in the basic theory: the direct combustion technology in which the solid-phase mass in the coal is combined with the thermo decomposition gas-phase mass and therefore burned in the same one hearth betrays the nature and law of gas-phase mass or solid-phase mass respective. The completeness of the direct combustion requires excess air (α≧1.2). which results in a great number of poisonous and hazardous pollutants (SO_(x), NO_(x) and so on) related to oxygen produced during the combustion and then controlling them again. In so doing, the process is not only complicated, but also the cost is high and even a following status is caused: “controlling pollution and producing pollution”, discharge is unstable and pollution control is unable to reach the standard.

At present, the worldwide developing coal-based IGCC technology is of high power-generating efficiency but of a less benefits. Meanwhile its promotion and realization is limited a great deal. The essential reason thereof lies in utilization of the traditional coal gasification technology with high specific surface, high temperature and high pressure.

As to the above mentioned technology, worldwide conventional efficiency and common standard is balanced in the following way: maximizing (Q_(energy of used coal))/(Q_(original total amount of energy of coal)) and minimizing (B_(discharging amount of pollutants using coal))/(B_(total amount of original pollutants of coal))

SUMMARY OF THE INVENTION

In view of the above mentioned status, the present invention proposes an idea of energy and environment protection efficiency during utilizing coal in a following way: controlling the following ratio the same time so that the former is maximized and the latter is minimized:

(Q _(energy of used coal))/(Q _(original total energy of coal) +Q _(total consumed energy as utilizing coal))(B _(pollutants discharging amount as utilizing coal) +B _(total amount of controlled pollutant discharged))/(B _(total amount of original pollutants of coal)).

Therefore, a thorough quantization check and development. A power generating method of coal gasification combustion boiler designed from the level of molecules from process innovation. The advantages of the process are: the pollutions are controlled in the origin, the elements are reduced in quantity, and environment protection and energy savings are achieved with high efficiency.

The technical route for this objective is that first the raw coal with desulfurization agents is carried to the molecular gasifier so as to be desulfurized and gasified into a clean heated (hot) coal gas and then is sprayed into a boiler to be burned; the high temperature smoke and gas will pass the heated surface of the boiler to exchange heat and then go out of the chimney; the steam (hot water) produced in the boiler will drive the gas turbine to power generation (heat supply).

The molecular gasifier adopts a mechanism of a complete oxidization of a thin bed with a large interface matching a positive reduction of a thick bed with a small cross section to produce gas. The molecular gasifier is provided on the upper reduction zone thereof with an annular point measuring temperature and is correspondingly provided on the lower oxidation zone thereof with an annular hole for spraying steam. During operation, an adjustment can be made with steam depending on the change of temperature on the measurement point so as to meet timely and equally process requirements to ensure the gasification reaction to stably proceed; the molecular gasifier can desulfurize the coal in the absence of oxygen when the ratio in component of Ca and S approaches 1. The heated coal gas in the hearth of the boiler is burned by adoption of low excess air ratio α approaching 1 so that 10 percent or more air can be saved and the poisonous and hazardous mass related to oxygen can be reduced. The boiler is on the lower part with a housing to remove coke (dust) which plays a role of refining coke or removing dust. During operation, depending on the quality and need, the coke refining can be selected and at any time the function of combustion dust removal can be turned on.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a flow chart of a power generating method of a typical gasification combustion boiler of the present invention;

FIG. 2 is a view of a typical improved molecular gasifier and an adjusting system of the present invention;

FIG. 3 is a structural view of a typical combustor provided on two sides symmetrically of the boiler of the present invention;

FIG. 4 is a structural view of a typical combustor provided on three sides of the boiler of the present invention;

FIG. 5 is a structural view of a combustor provided on one side of the boiler of the present invention;

FIG. 6 is a structural view of a typical combustor provided on four sides symmetrically of a super large boiler of the present invention;

BEST CARRIED-OUT EXAMPLES

Referring to the drawings 1, 2, 3 and the present invention is more detailed described.

The raw coal can be divided by a sieving process into a particle coal A and powered coal with a diameter of less than 10 mm. Powdered coal is combined with calcium so that the ratio in component between Ca and S approaches 1 and is produced into a coal ball B and hence the coal ball B is baked by the exhaust heat into a dry coal ball c with qualified moisture content (this preparation system for coal can save more 50% electricity than powder produced by coal), and the particle coal A and dry coal ball C are carried into molecular gasifier 1 by a coal-adding machine to produce gas. The gasification agents are carried through a grate from the bottom of the boiler (the pressure of the gasification agent for producing combustion gas is lower than 0.5 kpa which is a decrease of 58% compared to the wind pressure of the combustion technology of the current powdered coal and fluidization bed which is higher than or equal to 1.2 kpa, therefore the respective saving electricity ratio is 58%). The coke is discharged out of the bottom of the boiler by the grate. The molecular gasifier 1 uses an innovative complete oxidization 1-6 of a thin bed with a large interface matching to a positive reduction reaction 1-5 of a thick bed with a small cross section to produce gas, which is a gasification process designed from the molecular level and ensures a sequential operation of the reaction inside the boiler and hence increases with high efficiency the gasification (the electricity consumption is less than 1% of that of current gasification with high temperature, high pressure and fluidization bed in terms of the same quality of coal, the same production amount). The complete oxidization of the thin bed with a large interface 1-6 distributes the raw material into a thin bed with a large surface area by means of the structure of the lower oxidization section of the molecular gasifier 1, which causes a first interface in contact with the gasification agents sprayed into inner grate 1-8 of the boiler and outer grate 1-7 of the boiler to be enlarged and therefore speed up the operation speed of the oxidization reaction of C+O2=CO2+Q and makes it more complete. The positive reduction reaction 1-5 of the thick bed with a small cross section is formed and realized by the upper structure of the molecular gasifier 1, and extends the time of contact between reaction mass in CO2+C=2CO-Q and increases the speed of the ascending hot liquid and hence speeds up the effect of the heat convection and the mass transfer by convection so that the temperature of the pillar-form raw material under reduction reaction is increased and meanwhile the carbon dioxide in the reaction material can be rapidly compensated. Due to the factors mentioned above, the speed of the reduction reaction is increased so that the reaction is complete and full. In order to meet process requirements and to balance the reaction temperature, the molecular gasifier 1 is provided on the upper reduction zone with an annular point of temperature measurement 1-2 corresponding to an annular steam spraying hole 1-1 provided on the oxidization zone thereof. During operation, when measured temperature on the measurement point goes beyond the required value and the annular temperature difference goes beyond a fixed value (depending on the quality of the coal), the controlling system automatically (manually) turns on the lower jet duct 1-1 to use the steam to enter the adjusting course (this regional adjustment is timely, accurate and effective). The molecular gasifier 1 desulfurizes the coal by adding calcium to produce the gas in the absence of oxygen and hence the following component ration can be designed based on the sulfur content ratio and discharging standard of the raw coal: the ratio of Ca and S approaches 1 so that the target of desulfurization is reached with high efficiency. The coke containing calcium can be discharged out of the bottom of the boiler by the grate to be reused as a raw material of cement. The hot coal gas enters into the outer combustor 2 and passes the housing 6 of coke removal or the combustion chamber 6 of dust removal (the dust removal housing 6 can have two functions of refining coke and removing dust: 1 in accordance with the coal quality and as desired, the air valve of the outer combustor 2 is switched off so that the housing 6 refines coke by the effect of impact drive force, the obtained coke is a raw material for production of coal-based active charcoal; 2 it can also can be switched to other functions as desired to activate and adjust the air to cooperate with the hot coal gas for the combustion and removing dust) and goes into the inner combustor 5 again to be burned completely. The coal gas is produced by the combustion with low excess air efficient a approaching 1 (in so doing, 10% or more air can be saved and respectively the poisonous and hazardous material related to oxygen such as SOx, NOx is decreased). The hot coal gas with high temperature passes the heated side of the boiler 3 to exchange the heat and goes out of the chimney. During the gasification combustion, a precaution of pollution is given in the origin and the elements are decreased and hence a high efficiency environment protection and saving energy is realized. The steam (hot water) produced by the boiler 3 drives the gas turbine to generate power (to supply heat).

FIG. 2 is view of a typical improved molecular gasifier 1 and controlling system, the reference numeral 1-1 designates the annular steam spraying hole; 1-2 the annular temperature measurement hole; 1-3 coal adding port; 1-4 exit of the coal gas; 1-5 the reduction reaction zone of thick bed with a small cross section; 1-6 the oxidization zone of the thin bed with a large interface; 1-7 outer grate; 1-8 inner grate; the coke is discharged out of the bottom of the boiler; the gasification agent is sprayed into through the grate. Such molecular gasifier 1 and gasification method not only produces clean hot coal gas and ensures to obtain a high-efficiency combustion boiler and various furnace, but also can be utilized cooperatingly in the power generating system of the gas interior combustion engine and the gas turbine to produce the desired cold coal gas and raw chemical gas. The amount of gasification is high and the strength of gasification is 1000-2600 kg/m²·h and large scale of the process can realized (some thousand ton of production per single boiler and each day). The operation cost is low (the electricity consumption is less than 1% of that of the gasification bed and fluidization bed with similar coal quality and similar output of production).

FIG. 3 is a structural view of a typical combustor provided symmetrically on two sides of the boiler of the present invention. 2 designates the outer combustor which can be switched on/off and adjust the air to spray and blow downward the coal gas; 3 the hearth of the boiler; 4 coke removal hole or dust removal hole; 5 inner combustor; 6 the housing for removing coke or combustion chamber for removing dust; 7 the coal gas cavity of the combustor; 8 the air chamber of the combustor; 9 the wall of the combustor which is provided with air spraying holes; 10 the air chamber of the inner combustor.

FIG. 4 is a structural view of a typical combustor provided on three sides of the boiler of the present invention. 2 designates the outer combustor spraying and blowing downwardly; 3 the hearth of the boiler.

FIG. 5 is a structural view of a typical combustor provided on one side of the boiler of the present invention. 2 designates the outer combustor spraying and blowing downwardly, 3 the hearth of the boiler.

FIG. 6 is a structural view of a typical combustor provided on three sides of the super large scale boiler of the present invention. 2 designates the outer combustor spraying and blowing downwardly, 3 the hearth of the boiler.

Due to the carbon-molecular gasification combustion technology, the precaution from the origin is realized and the elements are decreased. The pollution is scientifically resolved and the environment protection and energy saving is kept in the whole course. The cost is low and the long-term operation is stable and liable. The invention can also gasify and burn various coal, biological substance and other organics (waste). The invention can refine the coke and remove the dust alternatively in accordance with the need and the coal quality.

Therefore, the present invention has a wide usage almost in all the domestic market and in various equipment using coal, oil, gas and electricity as fuel. Furthermore, the benefits of environmental protection and economical benefits are large. 

1. A power generating method of Carbon-molecule gasification combustion, the method comprising the following main steps: step 1: adding a desulfurizing agent to coal, and conducting desulfiurization and gasification in a molecular gasifier to produce a hot coal gas and a coke dust wherein; the structure of the molecular gasifier is designed so that inside the gasifier the complete oxidization of a thick bed with a large interface designed in the molecular level matches the positive reduction reaction of a thick bed with a small cross section; the molecular gasifier can desulfurize the coal in the absence of the oxygen where the ratio between Ca and S in the desulfurizing agent approaches 1; the molecular gasifier is provided with a regional adjusting means comprising an annular temperature measurement hole on the upper reduction zone and an annular steam spraying hole correspondingly provided on lower oxidation zone wherein, depending the change of temperature measured on the temperature measurement point, an adjustment can be effected by means of steam to ensure a complete oxidation of the thin bed with a large interface matching the positive reduction of the thick bed with a small cross section steadily operate; a fuel for the molecular gasifier can be any one of various coal, biomass and other organic waste, step 2: mixing the hot coal gas and low excess air for combustion in a furnace of a boiler with more than one sides, after heat transfer via a heated side of the boiler, emitting a high temperature flue gas complying with the standard from a chimney, wherein a vapor generated by the boiler drives a steam turbine to generate power, said hot coal as is mixed with and burned with the low excess air with an air coefficient α which can approach a value of 1; step 3: wherein the boiler is provided on the lower part thereof with a coke removal chamber for coke dust refining and coke dust removal in accordance with coal quality and as desired, wherein the coke removal chamber for coke dust refining and coke dust removal is designed so as to interchange between the refining and the removal.
 2. A power generating method of carbon-molecule gasification combustion in accordance with claim 1, wherein the coke dust contains calcium from the desulfurization in the absence of air and can be used as the raw material of cement.
 3. The power generating method of Carbon-molecule gasification combustion in accordance with claim 1, wherein in the step 3, the coke removal chamber is provided on the too circumference thereof with an outer combustor which can turn on or off and adjust air to spray downward the heated coal gas and which can refine the coke dust with the effect of an impact drive force when an air valve of the outer combustor is turned off or remove the dust by a clean combustion of the hot coal gas and the air cooperating with the hot coal gas and adjusted and supplied at any time as desired; and wherein the outer combustor can be placed symmetrically on two sides or four sides of the boiler or furnace or on one side or three sides of the boiler of furnace. 4-6. (canceled)
 7. The power generating method of carbon-molecule gasification combustion in accordance with claim 1 wherein in the hot coal gas produced in step 1 can be used in various boilers or furnaces, or for producing a desired cold coal gas for use in gas inner combustion engines and gas turbines, or for producing a chemical raw material.
 8. A power generating method of Carbon-molecule gasification combustion in accordance with claim 1, wherein the following ratios are controlled so that the former is maximized and the latter is minimized: Q _(energy of used coal)/(Q _(original total energy of coal) +Q _(total consumed energy as utilizing coal))(B _(pollutants discharging amount as utilizing coal) +B _(controlled pollutants discharging total amount))/B _(total amount of original pollutants of coal). 